Efeito do estresse térmico e suplementação da dieta com arginina e vitamina C no desempenho e imunidade de frangos de corte
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Data
2020-09-04
Autores
Mello, Érica Santos
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Universidade Estadual Paulista (Unesp)
Resumo
A produção avícola no Brasil enfrenta um grande desafio que é o estresse por calor, ele pode afetar negativamente o sistema imunológico reduzindo o desempenho produtivo. O objetivo desse estudo foi avaliar os efeitos da suplementação da arginina e da vitamina C sobre o desempenho e resposta imune de frangos de corte em ambiente de termoneutralidade e estresse cíclico pelo calor. Foram utilizados 384 frangos de corte machos no período de 1 a 35 dias de idade. As aves foram distribuídas em delineamento inteiramente casualizado (DIC) em um esquema fatorial 3x2x2: 3 níveis de inclusão de arginina digestível (100, 130 e 160% da exigência da arginina), dois níveis de inclusão de vitamina C (0 e 200 ppm) e 2 temperaturas (termoneutralidade e estresse cíclico por calor) totalizando 12 tratamentos com 8 repetições de 4 aves cada. Foram avaliados índices zootécnicos, hemograma completo, perfil bioquímico sorológico, peso relativo dos órgãos imunes, histomorfometria Bursa de Fabricíus e expressão relativa dos genes HSP 70 e GPx utilizando-se o gene actina como controle interno. O estresse cíclico por calor teve impactos negativos nos frangos de corte, reduzindo o consumo de ração e, por consequência, o ganho de peso aos 21 e 35 dias. Aos 21 e 35 dias de idade a suplementação de 200 ppm de vitamina C na dieta dos frangos de corte melhorou o consumo de ração e o ganho de peso dos frangos, entretanto, não influenciou o peso dos órgãos imunes e as concentrações séricas de glicose, colesterol e creatina quinase. Aos 35 dias de idade, a suplementação da arginina não influenciou o desempenhos dos frangos, o peso dos órgãos, a concentração de glicose e de creatina quinase, mas influenciou a concentração sérica de colesterol. A vitamina C e a Arginina aumentaram a percentagem da área do córtex da Bursa. E a inclusão de arginina e vitamina C aumentou a expressão genica HSP 70 e do GPx. Conclui-se os frangos de corte quando recebem vitamina C sofrem uma resposta ao estresse menos severa após exposição a altas temperaturas e a suplementação de Arginina e vitamina C aumentou a expressão genica do HSP 70 dando maior resistência as aves durante períodos de calor e a expressão de GPx que indicando um aumento na atividade antioxidante de frangos de corte.
Brazilian poultry production faces a major challenge that is heat stress, it affects negatively the immune system, reducing productive performance. The aim of this study was to evaluate supplementation of arginine and vitamin C effects on performance and immune response of broilers in thermoneutrality and cyclic heat stress environments. A total of 384 male broilers from 1 to 35 days of age were allotted in a 3x2x2 completely randomized factorial scheme: 3 digestible arginine levels (100, 130 and 160% of the requirement), two vitamin C levels (0 and 200 ppm) and 2 temperatures (thermoneutrality and cyclic heat stress), totaling 12 treatments with 8 repetitions of 4 birds each. Zootechnical indexes, complete blood count, serological biochemical profile, relative weight of immune organs, Bursa of Fabricius histomorphometry and relative expression of HSP 70 and GPx genes, using the actin gene as an internal control, were evaluated. Cyclic heat stress had negative impacts on broilers, reducing feed intake and, consequently, weight gain at 21 and 35 days. At 21 and 35 days of age, supplementation of 200 ppm of vitamin C improved feed intake and weight gain, however, did not influence immune organs weight and serum glucose concentrations, cholesterol and creatine kinase. At 35 days of age, arginine supplementation did not influence the performance of the chickens, the organs weight, concentration of glucose and creatine kinase, but it did influence the serum concentration of cholesterol. Vitamin C and Arginine increased the Bursa cortex percentage. The inclusion of arginine and vitamin C increased HSP 70 and GPx gene expression. In conclusion, broilers when receiving vitamin C undergo a less severe stress response after exposure to high temperatures, and supplementation of arginine and vitamin C increased the genetic expression of HSP 70 promoting greater resistance during periods of heat. The expression of GPx indicates an increase in antioxidant activity of broilers.
Brazilian poultry production faces a major challenge that is heat stress, it affects negatively the immune system, reducing productive performance. The aim of this study was to evaluate supplementation of arginine and vitamin C effects on performance and immune response of broilers in thermoneutrality and cyclic heat stress environments. A total of 384 male broilers from 1 to 35 days of age were allotted in a 3x2x2 completely randomized factorial scheme: 3 digestible arginine levels (100, 130 and 160% of the requirement), two vitamin C levels (0 and 200 ppm) and 2 temperatures (thermoneutrality and cyclic heat stress), totaling 12 treatments with 8 repetitions of 4 birds each. Zootechnical indexes, complete blood count, serological biochemical profile, relative weight of immune organs, Bursa of Fabricius histomorphometry and relative expression of HSP 70 and GPx genes, using the actin gene as an internal control, were evaluated. Cyclic heat stress had negative impacts on broilers, reducing feed intake and, consequently, weight gain at 21 and 35 days. At 21 and 35 days of age, supplementation of 200 ppm of vitamin C improved feed intake and weight gain, however, did not influence immune organs weight and serum glucose concentrations, cholesterol and creatine kinase. At 35 days of age, arginine supplementation did not influence the performance of the chickens, the organs weight, concentration of glucose and creatine kinase, but it did influence the serum concentration of cholesterol. Vitamin C and Arginine increased the Bursa cortex percentage. The inclusion of arginine and vitamin C increased HSP 70 and GPx gene expression. In conclusion, broilers when receiving vitamin C undergo a less severe stress response after exposure to high temperatures, and supplementation of arginine and vitamin C increased the genetic expression of HSP 70 promoting greater resistance during periods of heat. The expression of GPx indicates an increase in antioxidant activity of broilers.
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Palavras-chave
Ácido ascórbico, Aminoácido funcional, Antioxidante, Expressão gênica, Ascorbic acid, Functional amino acid, Antioxidant, Gene expression